Flames can only burn so hot. The highest temperature recorded is two trillion kelvins. A supernova can exceed 100 billion degrees, and you're hotter than that.
Your body temperature has a secondary breaker effect that can be manipulated as a sort of field to contain your heat, extending upwards of 100 meters.
Your heat is enough to even start in the deconstruction and softening of Endbringer cores, very likely to even turn an Endbringer into nothing more than a gas.
Your range is as your eye can see, and your abilities mean you are completely immune to the very idea of heat. No amount of heat can scar or burn you. Your infernos are all under your control.
You can scale this temperature down.
You have no brute or breaker powers allowing you to survive extremes, but you are immune to any malignant effects heat might cause to your health. This includes smoke from fires.